Methods and apparatus related to a side-fire member having a doped silica component

ABSTRACT

In one embodiment, an apparatus may include an optical fiber that may have a surface non-normal to a longitudinal axis of a distal end portion of the optical fiber. The surface may define a portion of an interface configured to redirect electromagnetic radiation propagated from within the optical fiber and incident on the interface to a direction offset from the longitudinal axis. The apparatus may also include a doped silica cap that may be fused to the optical fiber such that the surface of the optical fiber may be disposed within a cavity defined by the doped silica cap.

CROSS REFERENCE TO RELATED APPLICATION

This Nonprovisional Patent Application is a continuation of U.S.application Ser. No. 13/718,630, Dec. 18, 2012, which is a continuationof U.S. application Ser. No. 12/948,138, now U.S. Pat. No. 8,358,890,Nov. 17, 2010, which claims the benefit of priority under 35 U.S.C. §119to U.S. Provisional Patent Application No. 61/262,397, filed Nov. 18,2009, and titled “METHODS AND APPARATUS RELATED TO A SIDE-FIRE MEMBERHAVING A DOPED SILICA COMPONENT,” all of which are incorporated hereinby reference in their entireties.

FIELD

Embodiments relate generally to optical medical devices, and, inparticular, to side-firing optical fibers and methods for using suchdevices.

BACKGROUND

During some laser-based surgical procedures, a side-firing optical fibercan provide a medical practitioner with more control when applying laserenergy to a treatment area than a straight-firing optical fiber. Passingthe distal end portion of the side-firing optical fiber through anendoscope during surgery, however, may damage, scratch, degrade, and/ordeform the distal end portion. A capillary and/or a metal cap orcannula, usually made of surgical (e.g., medical) grade stainless steeland having a transmissive window, made of an optically transmissivematerial, can be placed over the distal end portion of the side-firingoptical fiber to protect the distal end portion. Once the distal endportion is properly positioned for treatment, laser energy can beapplied via the side-firing optical fiber to the target area.

During use of the device, a portion of the laser energy can leak intothe capillary and/or the metal cap at the distal end portion of the sidefiring optical fiber. This leakage of laser energy can reduce theefficiency with which laser energy is delivered to the treatment areaand/or increase overheating of the metal cap that is typically used toprotect the distal end portion. In some instances, overheating that canresult from laser energy leakage can affect the mechanical and/oroptical properties of the side-firing optical fiber. In other instances,the overheating that can occur from the laser energy leakage can besufficiently severe to damage the capillary and/or the metal cap at thedistal end portion of the side-firing optical fiber.

Thus, a need exists for a side-firing optical fiber distal end portionthat can increase device longevity, increase laser energy transmissionefficiency, reduce overheating, and/or increase patient safety.

SUMMARY

In one embodiment, an apparatus may include an optical fiber that mayhave a surface non-normal to a longitudinal axis of a distal end portionof the optical fiber. The surface may define a portion of an interfacewhich may be configured to redirect electromagnetic radiation propagatedfrom within the optical fiber and incident on the interface to adirection offset from the longitudinal axis. The apparatus may alsoinclude a doped silica cap that may be fused to the optical fiber suchthat the surface of the optical fiber may be disposed within a cavitydefined by the doped silica cap.

In some embodiments, the surface and the doped silica cap may define anenclosure. In some embodiments, the doped silica cap may have an indexof refraction less than an index of refraction associated with acladding layer of the optical fiber. In some embodiments, the dopedsilica cap may be fused to a cladding layer of the optical fiber.

In some embodiments, the doped silica cap may be adhesively coupled to acladding layer of the optical fiber. In some embodiments, the dopedsilica cap may be fused to an outer-layer portion of the optical fiber.The doped silica cap may be a fluorine-doped silica cap which may have aconcentration of fluorine greater than a concentration of fluorine ofthe outer-layer portion of the optical fiber.

In some embodiments, the interface may be a first interface and thedoped silica cap may be fused to a cladding layer of the optical fiber.The doped silica cap and the cladding layer may define a secondinterface such that electromagnetic radiation propagated within thecladding layer and incident on the second interface may be substantiallyinternally reflected within the cladding layer.

In some embodiments, the surface may be disposed within a distal endportion of the doped silica cap and a proximal end portion of the dopedsilica cap may be fused to the optical fiber. In some embodiments, thesurface may be included in the distal end portion of the optical fiber.In addition, the doped silica cap may be fused to a portion of theoptical fiber proximal to the distal end portion of the optical fiberwithout being fused to the distal end portion of the optical fiber.

In some embodiments, the apparatus may include a metallic cap coupled tothe doped silica cap. The metallic cap may have an inner surfaceconfigured to redirect electromagnetic radiation incident on the innersurface of the metallic cap into the cavity defined by the doped silicacap.

In some embodiments, the apparatus may include a metallic cap coupled tothe doped silica cap. The metallic cap may have an opening aligned withthe direction such that the electromagnetic radiation may be transmittedthrough the opening.

In another embodiment, a method includes receiving an optical fiber thatmay have a surface non-normal to a longitudinal axis of a distal endportion of the optical fiber. A doped silica component may be moved overthe surface of the optical fiber such that the surface of the opticalfiber may be disposed within a bore. The method may also include heatingthe doped silica component and the optical fiber such that at least aportion of an inner surface of the doped silica component defined by thebore may be fused to at least a portion of an outer surface of theoptical fiber.

In some embodiments, the moving may include moving until the surface ofthe optical fiber may be disposed within the bore of the doped silicacomponent. In some embodiments, the portion of the inner surface of thedoped silica component defined by the bore may be included in a proximalend of the doped silica component. In addition, the bore of the dopedsilica component may be a bore therethrough. The method may also includedefining an enclosure at a distal end of the doped silica component.

In some embodiments, the portion of the inner surface of the dopedsilica component defined by the bore may be included in a proximal endof the doped silica component. The bore of the doped silica componentmay be a bore therethrough. The method may also include heating a distalend of the doped silica component such that an enclosure may be definedby the distal end of the doped silica component and the optical fiber.

In some embodiments, the doped silica component may be cut from afluorine-doped preform. In addition, the outer surface of the opticalfiber may be associated with a fluorine-doped cladding layer. In someembodiments, the heating may define an interface and the doped silicacomponent may have a doping concentration such that electromagneticradiation from the optical fiber and incident on the interface may besubstantially internally reflected.

In some embodiments, the method may include moving an outer cap over thedoped silica component. The outer cap may be substantially opaque tolaser energy transmitted from the optical fiber.

In some embodiments, the surface may define a portion of an interfaceconfigured to redirect electromagnetic radiation propagated from withinthe silica-based optical fiber and incident on the interface to alateral direction offset from the longitudinal axis. The method may alsoinclude moving an outer cap over the doped silica component such that anopening defined by the outer cap may be aligned with the lateraldirection. In some embodiments, the doped silica component may be adoped silica cap.

In another embodiment, an apparatus includes a doped silica cap and adistal end portion of an optical fiber that may have a surface disposedwithin the doped silica cap. The surface may define at least a portionof an interface configured to redirect laser energy from a first portionof an optical path to a second portion of the optical path non-parallelto the first portion of the optical path. In addition, the secondportion of the optical path may intersect an outer surface of the dopedsilica cap.

In some embodiments, at least a portion of an inner surface of the dopedsilica cap may be heat-fused to at least a portion of an outer surfaceof the distal end portion of the optical fiber. In some embodiments, atleast a portion of an inner surface of the doped silica cap and at leasta portion of an outer surface of the distal end portion of the opticalfiber may define an interface. The doped silica cap may have a dopingconcentration such that electromagnetic radiation from the optical fiberand incident on the interface may be substantially internally reflected.

In some embodiments, at least a portion of the doped silica cap may beadhesively coupled to at least a portion of the distal end portion ofthe optical fiber. In some embodiments, the doped silica cap may be afluorine-doped silica cap.

In some embodiments, the apparatus may also include an outer capdisposed over at least a portion of the doped silica cap. In addition,the outer cap may be substantially opaque to laser energy. In someembodiments, the apparatus may also include a metallic cap disposed overat least a portion of the doped silica cap. The second portion of theoptical path may intersect an opening of the metallic cap.

In yet another embodiment, a method may include inserting a distal endportion of an optical fiber into a patient's body. The optical fiber mayhave a surface disposed within a doped silica cap. The surface maydefine at least a portion of an interface configured to redirect laserenergy from a first portion of an optical path to a second portion ofthe optical path non-parallel to the first portion of the optical path.The method may also include, after the inserting, activating a lasersource such that laser energy may be transmitted along the optical pathinto the patient's body. In some embodiments, the doped silica cap maybe a fluorine-doped silica cap.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. For example, the side-firing system described herein mayinclude various combinations and/or sub-combinations of the componentsand/or features of the different embodiments described. Althoughdescribed with reference to use for treatment of symptoms related toBPH, it should be understood that the side-firing system and theside-firing optical fibers, as well as the methods of using theside-firing system and the side-firing optical fibers may be used in thetreatment of other conditions. Additional objects and advantages of thedisclosure will be set forth in part in the description which follows,and in part will be obvious from the description, or may be learned bypractice of the disclosure. The objects and advantages of the disclosuremay be realized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thedisclosure and together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a side-tire system, according to anembodiment.

FIG. 2 is a side cross-sectional view of a distal end portion of aside-fire member that has a doped silica component, according to anembodiment.

FIG. 3 is a schematic diagram that illustrates a side cross-sectionalview of a distal end of a side-fire member, according to an embodiment.

FIG. 4 is a schematic diagram that illustrates an exploded view of adistal end of a side-fire member, according to an embodiment.

FIG. 5A is a schematic diagram that illustrates a doped silica componentand an optical fiber before the doped silica component is disposed overthe optical fiber, according to an embodiment.

FIG. 5B is a schematic diagram that illustrates a doped silica componentafter being disposed over an optical fiber, according to an embodiment.

FIG. 5C is a schematic diagram that illustrates a distal end of a dopedsilica component being heated and pulled, according to an embodiment.

FIG. 5D is a schematic diagram that illustrates an outer cover and adoped silica component heat-fused to an optical fiber, according to anembodiment.

FIG. 6 is a flowchart that illustrates a method for producing a distalend of a side-fire member, according to an embodiment.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments(exemplary embodiments) of the disclosure, examples of which areillustrated in the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings to refer to thesame or like parts.

The devices and methods described herein are generally related to anoptical fiber configured to treat an area within a body of a patient.Specifically, the optical fiber can be used to transmit laser energyfrom a laser source to a target treatment area that is disposed lateralto a distal end portion of the optical fiber. One end of the opticalfiber, the proximal end portion, can be coupled to the laser sourcewhile the other end of the optical fiber, the distal end portion, can beinserted into the patient's body to provide the laser treatment.

The optical fiber can have a surface non-normal to a longitudinal axisof a distal end portion of the optical fiber. The surface can bereferred to as an angled surface and can be at the distal end of theoptical fiber. The angled surface can define a portion of an interface(can be referred to as a reflective interface) configured to redirectlaser energy propagated from within the optical fiber and incident onthe interface to a direction offset (e.g., a lateral direction, aside-firing direction) from the longitudinal axis toward the targettreatment area. The laser energy redirected via the interface can bereferred to as lateral laser energy, redirected laser energy, orside-fired laser energy. Because the optical fiber is configured toredirect laser energy in, for example, a lateral direction, the opticalfiber can be referred to as a side-firing optical fiber. In someembodiments, the distal end portion of the optical fiber can be referredto as a side-firing portion or a laterally-firing portion. The opticalfiber and/or laser source can be included in an optical fiber system(also can be referred to as a side-fire system).

The angled surface of the optical fiber can be disposed within a dopedsilica component (e.g., a doped silica cap) that is fused to the opticalfiber. Redirected laser energy can be transmitted through a portion ofthe doped silica component. The doped silica component and the angledsurface of the optical component can define an enclosure. An index ofrefraction of the doped silica component can be defined to promote totalor substantially total internal reflection of, for example, leaked/straylaser energy from within the optical fiber and incident on an interfacedefined by the doped silica component and optical fiber. By internallyreflecting the leaked/stray laser energy, the leaked/stray energy can besubstantially prevented from, for example, adversely affecting themechanical and/or optical properties of the side-tiring optical fiber.In some embodiments, the index of refraction can be defined at least inpart by a doping concentration of a dopant (e.g., a fluorine dopant, achlorine dopant, a rare-earth dopant, a germanium dopant, an alkalimetal dopant, an alkali metal oxide dopant, etc.) within the silicacomponent. The optical fiber can be optionally doped with any dopantthat can be used to dope the silica component (to make a doped silicacomponent), and vice versa.

In some embodiments, the doped silica component can be at leastpartially formed after being fused to an optical fiber that has anangled surface. In some embodiments, a doped silica cap can be formedfrom, for example, a doped silica pre-form before being fused to anoptical fiber that has, for example, an angled surface. In someembodiments, an outer cover, such as a metallic cap or ceramic cap, canbe coupled to the doped silica component. The outer cover can besubstantially opaque to a spectral region of electromagnetic radiationassociated with the laser energy propagated within the optical fiber.The outer cover can have a transmissive portion (e.g., a window) throughwhich redirected laser energy can be transmitted.

The devices and methods described herein can be used in treatingsymptoms related to, for example, an enlarged prostate gland, acondition known as Benign Prostatic Hyperplasia (BPH). BPH is a commoncondition in which the prostate becomes enlarged with aging. Theprostate is a gland that is part of the male reproductive system. Theprostate gland includes two lobes that are enclosed by an outer layer oftissue and is located below the bladder and surrounding the urethra, thecanal through which urine passes out of the body. Prostate growth canoccur in different types of tissue and can affect men differently. As aresult of these differences, treatment varies in each case. No cure forBPH exists, and once the prostate begins to enlarge, it often continues,unless medical treatment is initiated.

Patients who develop symptoms associated with BPH generally require someform of treatment. When the prostate gland is mildly enlarged, researchstudies indicate that early treatment may not be needed because thesymptoms can clear up without treatment in as many as one-third ofcases. Instead of immediate treatment, regular checkups are recommended.Only if the condition presents a health risk, or the symptoms result Inmajor discomfort or inconvenience to the patient, is treatment generallyrecommended. Current forms of treatment include drug treatment,minimally-invasive therapy, and surgical treatment. Drug treatment isnot effective in all cases and a number of medical procedures have beendeveloped to relieve BPH symptoms that are less invasive thanconventional surgery.

While drug treatments and minimally-invasive procedures have provenhelpful for some patients, many doctors still recommend surgical removalof the enlarged part of the prostate as the most appropriate long-termsolution for patients with BPH. For the majority of cases that requiresurgery, a procedure known as Transurethral Resection of the Prostate(TURP) is used to relieve BPH symptoms. In this procedure, the medicalpractitioner inserts an instrument called a resectoscope into andthrough the urethra to remove the obstructing tissue. The resectoscopealso provides irrigating fluids that carry away the removed tissue tothe bladder.

More recently, laser-based surgical procedures employing side-firingoptical fibers and high-power laser sources have been used to removeobstructing prostate tissue. In these procedures, a doctor passes theoptical fiber through the urethra using a cystoscope, a specializedendoscope with a small camera on the end, and then delivers multiplebursts of laser energy to destroy some of the enlarged prostate tissueand to shrink the size of the prostate. Patients who undergo lasersurgery usually do not require overnight hospitalization, and in mostcases, the catheter is removed the same day or the morning following theprocedure. Generally, less bleeding occurs with laser surgery andrecovery times tend to be shorter than those of traditional proceduressuch as TURP surgery.

A common laser-based surgical procedure is Holmium Laser Enucleation ofthe Prostate (HoLEP). In this procedure, a holmium:YAG (Ho:YAG) laser isused to remove obstructive prostate tissue. The Ho:YAG surgical laser isa solid-state, pulsed laser that emits light at a wavelength ofapproximately 2100 nanometers (nm). This wavelength of light isparticularly useful for tissue ablation as it is strongly absorbed bywater. An advantage of Ho:YAG lasers Is that they can be used for bothtissue cutting and for coagulation. Another common laser surgeryprocedure is Holmium Laser Ablation of the Prostate (HoLAP), where aHo:YAG laser is used to vaporize obstructive prostate tissue. Thedecision whether to use HoLAP or HoLEP is based primarily on the size ofthe prostate. For example, ablation may be preferred when the prostateis smaller than 60 cubic centimeters (cc). Laser-based surgicalprocedures, such as HoLAP and HoLEP, are often preferred because theyproduce similar results to those obtained from TURP surgery while havingfewer complications and requiring shorter hospital stay, shortercatheterization time, and shorter recovery time.

It is noted that, as used in this written description and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise, Thus, for example, theterm “a wavelength” is intended to mean a single wavelength or acombination of wavelengths. Furthermore, the words “proximal” and“distal” refer to direction closer to and away from, respectively, anoperator (e.g., a medical practitioner, a medical practitioner, a nurse,a technician, etc.) who would insert the medical device into thepatient. Thus, for example, the optical fiber end inserted inside apatient's body would be the distal end of the optical fiber, while theoptical fiber end outside a patient's body would be the proximal end ofthe optical fiber.

FIG. 1 is a schematic diagram of a side-fire system 110, according to anembodiment. The side-fire system 110 can include a laser source 111, anoptical coupler 112, a side-fire member 114, and a distal end portion116. The side-firing system 110 also includes a suitable catheter orendoscope 115 for inserting the distal end portion 116 into a patient'sbody.

The laser source 111 can be configured to generate laser energy that canbe propagated within the side-fire member 114, for example, during asurgical procedure. The laser source 111 can include, for example, aHo:YAG laser source, a neodymium-doped: YAG (Nd:YAG) laser source, asemiconductor laser diode, and/or a laser source employing a non-linearelement (e.g., a laser source that includes a potassium-titanylphosphate crystal (KTP) laser source). In some embodiments, more thanone laser source can be used during a surgical procedure.

In some embodiments, the laser source 111 can also have a control module(not shown) configured to control (e.g., to set, to modify) a timing, awavelength, and/or a power of laser energy emitted from the laser source111. In some embodiments, the control module can also be configured toperform various functions such as laser selection, filtering,temperature compensation, and/or Q-switching. The control module can bea hardware-based control module and/or a software-based control modulethat can include, for example, a processor and/or a memory.

The side-fire member 114 can be coupled to the laser source 111 throughthe optical coupler 112. The optical coupler 112 can be, for example, aSub-Miniature A (SMA) connector. The proximal end of the side-firemember 114 can be configured to receive laser energy from the lasersource 111, and the distal end of the side-fire member 114 can beconfigured to output the laser energy 120 through the distal end portion116. The side-fire member 114 can include an optical fiber that has, forexample, a fiber core, one or more cladding layers disposed around thefiber core, a buffer layer disposed around the cladding layer(s), and ajacket (disposed around the buffer layer). In some embodiments, thebuffer layer can be referred to as a cladding layer.

In some embodiments, the fiber core can be made of a suitable materialfor the transmission of laser energy from the laser source 111. In someembodiments, for example, the fiber core can be made of silica with alow hydroxyl (OH⁻) ion residual concentration. Laser energy wavelengthsranging from about 500 nm to about 2100 nm can be propagated within thefiber core during a surgical procedure. An example of low hydroxyl(low-OH) fibers used in medical devices is described in U.S. Pat. No.7,169,140 to Kume, the disclosure of which is incorporated herein byreference in its entirety. The fiber core can be a multi-mode fiber coreand can have a step or graded index profile. The fiber core can also bedoped with a dopant (e.g., an amplifying dopant). The cladding can be asingle or a double cladding that can be made of a hard polymer orsilica. The buffer (which can function as a cladding layer) can be madeof a hard polymer or acrylate, for example. When the optical fiberincludes a jacket, the jacket can be made of Tefzel®, for example, orcan be made of other polymer-based substances.

The distal end portion 116 can include one or more surfaces that canindividually or collectively operate to redirect laser energy In adirection non-parallel (e.g., a lateral direction) to a longitudinalaxis or a centerline of the distal end of the fiber core. Such a surfacecan be an angled surface defined by, for example, the fiber core and/orone or more cladding layers about the fiber core. The angled surface canbe non-normal to a longitudinal axis of a. distal end portion of theoptical fiber. In some embodiments, the surface can be, for example, areflecting member with a multilayer dielectric coating on an angledsurface. More details related to a reflecting member are set forth inco-pending patent application Ser. No. 61/054,280, entitled,“Side-Firing Laser Fiber with Protective Tip and Related Methods,” filedMay 19, 2008, which is incorporated herein by reference in its entirety.

The surface(s) configured to redirect laser energy can be disposedwithin a doped silica component at the distal end portion 116 of theside-fire member 114. The doped silica component can be fused (e.g.,heat-fused) to a portion of the side-fire member 114. For example, thedoped silica component can be heat-fused to a cladding layer of theside-fire member 114. The doped silica component can define at least aportion of an enclosure. When the doped silica component defines atleast a portion of an enclosure, the doped silica component can bereferred to as a doped silica cap. In some embodiments, an outer cover,such as a metallic cap, can be coupled to an outer surface of the dopedsilica component.

In some embodiments, the endoscope 115 can define one or more lumens(sometimes referred to as working channels). In some embodiments, theendoscope 115 can include a single lumen that can receive therethroughvarious components such as the side-fire member 114. The endoscope 115can have a proximal end configured to receive the distal end portion 116of the side-fire member 114 and a distal end configured to be insertedinto a patient's body for positioning the distal end portion 116 of theside-fire member 114 in an appropriate location for a laser-basedsurgical procedure. For example, to relieve symptoms associated withBPH, the endoscope 115 can be used to place the optical-fiber distal endportion 116 at or near the enlarged portion of the prostate gland. Theendoscope 115 can include an elongate portion that can be sufficientlyflexible (or rigid) to allow the elongate portion to be maneuveredwithin the body.

The endoscope 115 can also be configured to receive various medicaldevices or tools through one or more lumens of the endoscope, such as,for example, irrigation and/or suction devices, forceps, drills, snares,needles, etc. An example of such an endoscope with multiple lumens isdescribed in U.S. Pat. No. 6,296,608 to Daniels at al., the disclosureof which is incorporated herein by reference in its entirety. In someembodiments, a fluid channel (not shown) is defined by the endoscope 115and coupled at a proximal end to a fluid source (not shown). The fluidchannel can be used to irrigate an interior of the patient's body duringa laser-based surgical procedure. In some embodiments, an eyepiece (notshown) can be coupled to a proximal end portion of the endoscope 115,for example, and coupled to a proximal end portion of an optical fiberthat can be disposed within a lumen of the endoscope 115. Such anembodiment allows a medical practitioner to view the interior of apatient's body through the eyepiece.

FIG. 2 is a side cross-sectional view of a distal end portion 216 of aside-fire member 214 that has a doped silica component 220, according toan embodiment. An outer cover 230 (e.g., a metallic cover, a plasticcover) may optionally be coupled to and disposed outside of the dopedsilica component 220. As shown in FIG. 2, laser energy P that ispropagated along a longitudinal axis (or centerline) of an optical fiber213 of the side-fire member 214 is redirected by an interface 218defined by an angled surface 217 and a gas (or a liquid) 224 within acavity defined by the doped silica component 220. In some embodiments,the gas can be air. The redirected laser energy Q is transmitted througha portion of the doped silica component 220 and an opening 232 definedby the outer cover 230. In other words, the laser energy P istransmitted within an optical path along the longitudinal axis (orcenterline) of the optical fiber 213, and the redirected laser energy Qis transmitted within an optical path that intersects the doped silicacomponent 220 and the opening 232. In some embodiments, the opticalpath(s) can include multiple segments. Although not shown, the opticalfiber 213 can have, for example, a fiber core, one or more claddinglayers about the fiber core, and/or a buffer layer (which can functionas a cladding layer or the only cladding layer).

An inner surface 225 of the doped silica component 220 is heat-fused toan outer surface 215 of the optical fiber 213. Specifically, the innersurface 215 is heat-fused over an entire area of the outer surface 215of the optical fiber 213 that is disposed within the doped silicacomponent 220 (except for the angled surface 217, which is not part ofthe outer surface 215). In other words, any portion of the outer surface215 of the optical fiber 213 that is substantially parallel to, anddisposed within the doped silica component 220, is fused to the innersurface 225 of the doped silica component 220. Because the optical fiber213 has an angled surface 217, a heat-fused length A along a top side ofthe optical fiber 213 is longer than a heat-fused length B along abottom side of the optical fiber 213.

In some embodiments, less than the entire area of the outer surface 215of the optical fiber 213 can be heat-fused to the inner surface 225 ofthe doped silica component 220. In some embodiments, a portion of theouter surface 215 of the optical fiber 213 that is proximal to a planeC, which is at a proximal end of the angled surface 217 andsubstantially normal to a longitudinal axis of the optical fiber 213,can be heat-fused to the doped silica component 220. In someembodiments, multiple locations along the outer surface 215 of theoptical fiber 213 can be heat-fused to the inner surface 225 of thedoped silica component 220. For example, a portion of the outer surface215 near the proximal end 222 of the doped silica component 220 and/or aportion of the outer surface 215 near the angled surface 217 can be heatfused to the inner surface of the doped silica component 220. In someembodiments, two or more circumferential portions of the outer surface215 can be heat-fused to the doped silica component 220. In someembodiments, the heat-fused portions do not continuously surround theoptical fiber 213. In other words, just a top portion (e.g., a firstportion) and/or a bottom portion (e.g., a portion opposite the firstportion) of the outer surface 215 of the optical fiber 213 can beheat-fused to the doped silica component 220. In some embodiments, aportion 223 of the doped silica component 220 and inner surface 225through which the laser will be directed may be heat-fused (to preventunwanted reflection from an unfused interface between the doped silicacomponent 220 and inner surface 225). The heat-fused area can besufficiently large to provide mechanical stability (e.g., resistance toshear forces) between the optical fiber 213 and the doped silicacomponent 220. As shown in FIG. 2, an interface 250 is defined by theinner surface 225 of the doped silica component 220 and an outer surface215 of the optical fiber 213.

The doped silica component 220 has an index of refraction less than anindex of refraction of the outer surface 215 of the optical fiber 213.In some embodiments, the doped silica component 220 can be doped with,for example, a concentration of fluorine. Because of the difference inthe indices of refraction, a portion of the laser energy P propagatedwithin the optical fiber 213 and incident on the interface 250 can betotally or substantially totally internally reflected within the opticalfiber 213. If the optical fiber 213 has a cladding layer (not shown), aportion of the laser energy P propagated within the cladding layer andincident on the interface 250 can be totally or substantially totallyinternally reflected within the cladding layer.

The angle of incidence of the redirected laser energy Q on the interface250 can be defined so that the redirected laser energy Q is transmittedthrough the interface 250 rather than reflected. As shown in FIG. 2, apath of the redirected laser energy Q can be substantially normal and/ornon-normal to the surfaces (e.g., the outer surface 215, the innersurface 225) that defined the interface 250. More details related tointernal reflection and angles of incidence are described in connectionwith FIG. 3.

The index of refraction of the doped silica component 220 can be definedby the concentration of a dopant (e.g., fluorine) within the dopedsilica component 220. In some embodiments, the doping concentration ofthe doped silica component 220 can be substantially uniform. In someembodiments, the doping concentration at the inner surface 225 of thedoped silica component 220 can be lower than, for example, an outersurface 227 of the doped silica component 220, and vice versa. Likewise,the index of refraction of the outer surface 215 of the optical fiber213 can be defined by a concentration of a dopant. In some embodiments,the doping concentration of the outer surface 215 of the optical fiber213 can be substantially uniform. In some embodiments, the Index ofrefraction, as defined by a dopant concentration, at the outer surface215 of the optical fiber 213 can be lower than, or higher than, forexample, at an inner portion of the optical fiber 213, and vice versa.

The outer cover 230 is configured to keep stray laser energy (e.g., aportion of stray laser energy from laser energy P) from beingtransmitted in an undesirable direction out of the side-fire member 214.The outer cover 230 can be, for example, adhesively coupled to,mechanically coupled to (e.g., mechanically coupled via a screw) and/orpress fit around the doped silica component 220. Accordingly, the outercover 230 can be substantially opaque to the laser energy P and/orconfigured to reflect and/or absorb stray laser energy within (e.g.,internal to) the distal end portion 216 of the side-fire member 214. Theouter cover 230 can be made of a metallic material such as a surgical(e.g., medical) grade stainless steel, a plastic, or other material withlike properties. In some instances, the outer cover 230 can be made of aceramic material (e.g., alumina) because certain ceramics have stablematerial characteristics at high-temperatures and/or have a highreflectance value at desirable operating wavelengths of the laser energyP. The outer cover 230 can also provide protection (e.g., mechanicalprotection) to the distal end portion 216 of the side-fire member 214.

In some embodiments, rather than an opening 232, the outer cover 230 caninclude a transmissive material (not shown) through which the redirectedlaser energy Q can be transmitted for surgical treatment. Thetransmissive material can be, for example, substantially transparent toa specified spectrum of electromagnetic radiation associated with theredirected laser energy Q. The transmissive material can define, forexample, a lens. In some embodiments, the transmissive material can betreated thermally, optically, mechanically, and/or chemically to definea desirable structural and/or optical characteristic. For example, theoptically-transmissive material can be thermally treated duringmanufacturing using emissions from, for example, a carbon dioxide (CO₂)laser source. The transmissive material can be defined such that theredirected laser energy Q can be delivered to a target area in adesirable fashion (e.g., delivered in a focused beam).

FIG. 3 is a schematic diagram that illustrates a side cross-sectionalview of a distal end 316 of a side-fire member, according to anembodiment. As shown in FIG. 3, an outer cover 330 is disposed outsideof a doped silica component 320. The doped silica component 320 isheat-fused to a cladding layer 312 that is disposed outside of a fibercore 310 of an optical fiber within the side-fire member. The opticalfiber has an angled surface 314 that is non-normal to a longitudinalaxis 393 of the distal end 316. As shown in FIG. 3, the angled surface314 and an air-filled cavity 372 define an interface 315 configured toredirect laser energy T that is propagated from within the optical fiberand is incident on the interface 315. The redirected laser energy 384 istransmitted through the doped silica component 320 and out of an opening332 within the outer cover 330. The cavity 372 can be defined by thedoped silica component 320 and the angled surface 314.

The doped silica component 320 has an index of refraction that is lessthan an index of refraction of the cladding layer 312. The index ofrefraction of the cladding layer 312 is less than an index of refractionof the fiber core 310 of the optical fiber. Accordingly, the laserenergy T that is incident on an interface 311 defined by the claddinglayer 312 and the fiber core 310 is internally reflected within thefiber core 310 as shown in FIG. 3. Portions of laser energy S that leakinto the cladding layer 312 are internally reflected by an interface 364defined by the doped silica component 320 and the cladding layer 312.

As shown in FIG. 3, at least a portion of the redirected laser energy384 is substantially or totally transmitted through at least a portionof the cladding layer 312 and at least a portion of the doped silicacomponent 320. In other words, an optical path of the redirected laserenergy 384 intersects at least a portion of the cladding layer 312 andat least a portion of the doped silica component 320. An angle ofincidence 392 (relative to a reference line normal to the interface 311and interface 364) of the redirected laser energy 384 is sufficientlysmall that the redirected laser energy 384 is substantially or totallytransmitted through the doped silica component 320.

As shown in FIG. 3, a portion of the laser energy S (from laser energyT) is leaked into the cladding layer 312. The laser energy S can also bereferred to as stray/leaked laser energy. The indices of refraction ofrefraction the cladding layer 312 and the doped silica component 320,respectively, are defined so that the laser energy S is internallyreflected within the cladding layer 312 rather than transmitted throughthe doped silica component 320 (and incident on the outer cover 330).This can prevent or reduce undesirable amounts of laser energy S frombeing transmitted through the doped silica component 320 and incident onthe outer cover 330, which in turn can prevent or reduce the distal end316 of the side-fire member from being damaged. For example, this canprevent or reduce the outer cover 330 from being overheated and canbecoming decoupled from the doped silica component 320.

In some embodiments, the indices of refraction of the cladding layer 312and the doped silica component 320, respectively, can be defined so thata desirable range of angles of incidence of the redirected laser energy384 will be transmitted through the doped silica component 320 whileunacceptable levels of laser energy S within the cladding layer 312 willnot be transmitted through the doped silica component 320. Because theinterface 364 is a total-internal-reflection interface, a relativelylarge inner surface area of the doped silica component 320 can beheat-fused to the cladding layer 312 with a substantially reducedpossibility that the stray laser energy S will be undesirablytransmitted into the doped silica component 320 through the heat-fusedarea. A relatively large heat-fused area promotes a strong bond betweenthe doped silica component 320 and the cladding layer 312 that can besubstantially resistant to tensile forces (e.g., forces in the distal orproximal direction along the longitudinal axis 393). If the index ofrefraction of the doped silica component were substantially equal tothat of the cladding layer, an undesirable (e.g., a damaging) percentageof the stray laser energy could be transmitted into the doped silicacomponent and incident on the outer cover; the amount of laser energytransmitted into the doped silica component would be substantiallyincreased with a larger heat-fused area.

As shown in FIG. 3, an angle of incidence 394 of the laser energy Tpropagated within the fiber core 310 (relative to a line normal tointerface 311 and interface 364) is sufficiently large that the laserenergy T is substantially or totally internally reflected within thefiber core. In some embodiments, the indices of refraction the fibercore 310 and the cladding layer 312, respectively, can be defined sothat a specified range of the angles of incidence that will reflect thelaser energy T within the fiber core 310 (or range of angles ofincidence that will transmit laser energy T through the cladding layer312) can be achieved,

An angle 396 of the angled surface 314 relative to the longitudinal axiscan be defined (e.g., determined, selected, designed) based on at leastone of several parameters. For example, the angle 396 can be definedbased on the wavelength of the laser energy T (and/or redirected laserenergy 384), the numerical aperture of the fiber core 310, the exit oroutput location for the redirected laser energy 384, anticipated angleof incidence of the laser energy T, and/or the optical properties of thedoped silica component 320. Moreover, the optical properties of theair-filled cavity 372 can also be used in determining an appropriateangle 396 for the angled surface 314. For example, an angle 396 of 35degrees can result in the laser or optical beam being laterallyreflected at an angle of about 70 degrees from the longitudinal axis 393of the distal end 316.

A fiber core 310 of the side-fire member can have an outer diameter G,for example, between approximately 20 micrometers (μm) to 1200 μm. Thecladding layer 312 can have a thickness F of between, for example,approximately 5 μm to 120 μm. In some embodiments, the outer diameter Hof the cladding layer 312 can be 1 to 1.3 times greater than the outerdiameter G of the fiber core 310. The doped silica component 320 canhave a thickness E of between, for example, approximately 5 μm toseveral millimeters. The outer cover 330 can have a thickness D ofseveral micrometers to several millimeters. Although not shown, in someembodiments, the outer cover 330 can include a low-profile cover (e.g.,a coating or a sleeve).

FIG. 4 is a schematic diagram that illustrates an exploded view of adistal end 416 of a side-fire member, according to an embodiment. Asshown in FIG. 4, the distal end includes an optical fiber 410, a dopedsilica component 420, and an outer cover 430. The optical fiber 410 hasan angled surface 414, and the outer cover 430 has a transmissiveportion 432. In some embodiments, the transmissive portion 432 can be anopening.

In some embodiments, the angled surface 414 of the optical fiber 410 canbe defined before the doped silica component 420 is moved over theoptical fiber 410 and heat-fused to the optical fiber 410. The angledsurface 414 can be, for example, mechanically defined by grinding and/orpolishing a distal end of a cleaved optical fiber using, for example, amechanical device (e.g., mechanical grinder) and/or a laser source.

As shown in FIG. 4, the doped silica component 420 has an opening 422(shown through the cut-away) at a proximal end 423. The doped silicacomponent 420 has a closed distal end 425 opposite the opening 422 atthe proximal end 423. In some embodiments, the closed distal end 425 canbe defined before the doped silica component 420 is moved over theoptical fiber 410 and heat-fused to the optical fiber 410. In someembodiments, the closed distal end 425 can be defined after the dopedsilica component 420 has been heat-fused to the optical fiber 410. Moredetails related to defining a closed distal end of a doped silicacomponent 420 after being heat-fused to an optical fiber 410 aredescribed in connection with FIGS. 5A-5D.

In some embodiments, the transmissive portion 432 can include atransmissive material (e.g., a lens) that is inserted into an openingwithin the outer cover 430. In some embodiments, the transmissivematerial can be inserted into the opening before the outer cover 430 ismoved over and coupled to the doped silica component 420. In someembodiments, the outer cover 430 can be, for example, adhesively bondedto the doped silica component 420. In some embodiments, the outer cover430 can be coupled to the doped silica component 420 before the dopedsilica component 420 is coupled to the optical fiber 410.

FIGS. 5A-5D are schematic diagrams that collectively illustrate a methodfor producing a side-fire member, according to an embodiment. FIG. 5A isa schematic diagram that illustrates a doped silica component 520 and anoptical fiber 510 before the doped silica component 520 is disposed overthe optical fiber 510, according to an embodiment. FIG. 5B is aschematic diagram that illustrates the doped silica component 520 afterbeing disposed (e.g., placed) over the optical fiber 510, according toan embodiment. As shown in FIG. 5A, the optical fiber 510 has an angledsurface 514 before the doped silica component 520 is disposed over theoptical fiber 510.

The doped silica component 520 has a bore 529 (e.g., a lumen) along alongitudinal axis 582 of the doped silica component 520. The bore 529 ofthe doped silica component 520 is in fluid communication with an openingat each end (along the longitudinal axis 582) of the doped silicacomponent 520. The doped silica component 520 can be cut from a lengthof a doped silica tubular (e.g., cylindrical) pre-form (not shown). Thedoped silica component 520 component can be cut from the pre-form using,for example, a laser energy cutting instrument or a mechanical cuttinginstrument. The pre-form can be cut along a plane that is substantiallynormal to a longitudinal axis of the pre-form.

In some embodiments, the doped silica component 520 can be uniformly ornon-uniformly doped with, for example, fluorine and/or another suitabledopant. In some embodiments, the doped silica component 520 can bebetween 50 mm to 10 cm long. In some embodiments, the doped silicatubular pre-form can have a doping concentration that is higher near aninner surface that defines the bore than at an outer surface of thepre-form.

In some embodiments, the size of the bore 529 can be increased beforebeing disposed over the optical fiber 510. In some embodiments, the sizeof the bore 529 can be increased by removing a portion of a walldefining the bore 529 with, for example, a reaming device. An innerdiameter of the bore 529 can be defined so that it is, for example, atleast a few micrometers larger than an outer diameter of the opticalfiber 510.

After the doped silica component 520 has been disposed over the opticalfiber 510, the doped silica component 520 can be heat-fused to theoptical fiber 510. In some embodiments, the doped silica component 520and optical fiber 510 can be heated using, for example, a heating source(e.g., a torch, an electrical heating element, a laser source) until thedoped silica component 520 and optical fiber 510 are fused. The dopedsilica component 520 and optical fiber 510 can be rotated about alongitudinal axis 584 of the optical fiber 510 while being heated.

FIG. 5C is a schematic diagram that illustrates a distal end 524 of thedoped silica component 520 being heated and pulled, according to anembodiment. The distal end 524 is being heated in a zone 574 while beingpulled in direction Y until an enclosure 572 (shown in FIG. 5D) isformed. In other words, a force in direction Y (away from the angledsurface 514) is applied on the distal end 524 while it is being Heated.The doped silica component 520 can be heated until the doped silicacomponent 520 softens and can be pulled. As the distal end 524 of thedoped silica component 520 is heated and pulled, the doped silicacomponent 520 plastically deforms until at least a portion of the distalend 524 is separated from the doped silica component 520 to define theshape of the doped silica component 520 shown in FIG. 5D.

In some embodiments, the heating and/or pulling discussed in connectionwith FIG. 5C are not performed coincidentally. For example, a portion ofthe distal end 524 can be heated before the distal end 524 is pulled. Insome embodiments, the optical fiber 510 and doped silica component 520can be rotated, for example, around the longitudinal axis 584 whilebeing heated and/or pulled. In some embodiments, the heating associatedwith FIG. 5B (during fusing) and the heating associated with FIG. 5C canbe performed using the same heating source and/or can be performedwithin the same heating cycle. In some embodiments, the heatingassociated with FIG. 5B and the heating associated with FIG. 5C can beperformed separately (e.g., different space and time) using differentheating sources.

FIG. 5D is a schematic diagram that illustrates an outer cover 530 and adoped silica component 520 heat-fused to an optical fiber 520, accordingto an embodiment. An enclosure 572 is defined by the angled surface 514and the doped silica component 520. As shown in 5D, the outer cover 530can be moved in direction Z and coupled to the doped silica component520. In some embodiments, at least a portion of a transmissive portion532 is disposed within (e.g., intersects) an optical path of laserenergy redirected by the angled surface 514.

FIG. 6 is a flowchart that illustrates a method for producing a distalend of a side-fire member, according to an embodiment. As shown in FIG.6, an optical fiber that has a surface non-normal to a longitudinal axisof a distal end portion of the optical fiber is received at 600. Thenon-normal surface can be referred to as an angled surface.

An inner surface of a bore of a doped silica component is moved over theangled surface of the optical fiber at 610 and the doped silicacomponent is coupled to the optical fiber at 620. In some embodiments, ashape and/or size of at least a portion of the bore can be changedbefore being moved over the angled surface and coupled to the opticalfiber.

A distal end of the doped silica component is heated and pulled todefine an enclosure at 630. The enclosure can be defined, at least inpart by the angled surface of the optical fiber and an inner surface ofthe doped silica component.

An outer cover is moved over the doped silica component at 640 and anopening of the outer cap is aligned with an optical path defined by theangled surface of the optical fiber at 650. The outer cover can be, forexample, adhesively bonded to the doped silica component.

Other embodiments of the disclosure will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosure herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention being indicated by the following claims.

What is claimed is:
 1. An apparatus, comprising: an optical fiberincluding a surface non-normal to a longitudinal axis of a distal endportion of the optical fiber, wherein the surface defines a portion ofan interface configured to redirect electromagnetic radiation propagatedfrom within the optical fiber and incident on the interface in adirection offset from the longitudinal axis; an intermediate cap fusedto an outer-layer portion of the optical fiber such that the surface ofthe optical fiber is disposed within a cavity defined by theintermediate cap, wherein the intermediate cap is a fluorine-dopedsilica cap, and the fluorine doped silica cap includes a concentrationof fluorine greater than a concentration of fluorine of the outer-layerportion of the optical fiber; and an outer cap coupled to theintermediate cap, wherein the outer cap includes an opening aligned withthe direction such that the electromagnetic radiation is transmittedthrough the opening.
 2. The apparatus of claim 1, wherein theintermediate cap has an index of refraction less than an index ofrefraction associated with a cladding layer of the optical fiber.
 3. Theapparatus of claim 1, wherein the outer-layer portion of the opticalfiber is a cladding layer of the optical fiber.
 4. The apparatus ofclaim 1, wherein the interface is a first interface and the outer-layerportion of the optical fiber is a cladding layer of the optical fiber,and wherein the intermediate cap and the cladding layer define a secondinterface such that electromagnetic radiation propagated within thecladding layer and incident on the second interface is substantiallyinternally reflected within the cladding layer.
 5. The apparatus ofclaim 1, wherein the surface is disposed within a distal end portion ofthe intermediate cap, and wherein a proximal end portion of theintermediate cap is fused to the optical fiber.
 6. The apparatus ofclaim 1, wherein the surface is included in the distal end portion ofthe optical fiber, and wherein the intermediate cap is fused to aportion of the optical fiber proximal to the distal end portion of theoptical fiber without being fused to the distal end portion of theoptical fiber.
 7. The apparatus of claim 1, wherein the outer cap is ametallic cap, and the metallic cap comprises an inner surface configuredto redirect electromagnetic radiation incident on the inner surface ofthe metallic cap into the cavity defined by the intermediate cap.
 8. Amethod, comprising: receiving an optical fiber, the optical fiberincluding a surface non-normal to a longitudinal axis of a distal endportion of the optical fiber; moving an intermediate component over thesurface of the optical fiber such that the surface of the optical fiberis disposed within a bore; heating the intermediate component and theoptical fiber such that at least a portion of an inner surface of theintermediate component defined by the bore may be fused to at least anouter-layer portion of the optical fiber, wherein the intermediatecomponent is a fluorine-doped silica cap, and the fluorine doped silicacap includes a concentration of fluorine greater than a concentration offluorine of the outer-layer portion of the optical fiber; and moving anouter cap over the intermediate component, wherein the outer cap issubstantially opaque to laser energy transmitted from the optical fiber.9. The method of claim 8, wherein the moving of the intermediatecomponent includes moving until the surface of the optical fiber isdisposed within the bore of the intermediate component.
 10. The methodof claim 8, wherein the portion of the inner surface of the intermediatecomponent defined by the bore is included in a proximal end of theintermediate component, and wherein, the bore of the intermediatecomponent is a bore therethrough.
 11. The method of claim 8, wherein theportion of the inner surface of the intermediate component defined bythe bore is included in a proximal end of the intermediate component,the bore of the intermediate component being a bore therethrough, themethod further comprising: heating a distal end of the intermediatecomponent such that an enclosure is defined by the distal end of theintermediate component and the optical fiber.
 12. The method of claim 8,wherein the heating defines an interface, and wherein the intermediatecomponent includes a doping concentration such that electromagneticradiation from the optical fiber and incident on the interface issubstantially internally reflected within the optical fiber.
 13. Themethod of claim 8, wherein the surface of the optical fiber defines aportion of an interface configured to redirect electromagnetic radiationpropagated from within the optical fiber and incident on the interfaceto a lateral direction offset from the longitudinal axis; the methodfurther comprising: moving an outer cap over the intermediate componentsuch that an opening defined by the outer cap is aligned with thelateral direction.
 14. An apparatus, comprising: a fluorine-doped silicacap; and a distal end portion of an optical fiber that includes asurface disposed within the doped silica cap, wherein the fluorine-dopedsilica cap is coupled to an outer-layer portion of the optical fiber,and the fluorine-doped silica cap includes a concentration of fluorinegreater than a concentration of fluorine of the outer-layer portion ofthe optical fiber; wherein the surface defines at least a portion of aninterface configured to redirect laser energy from a first portion of anoptical path to a second portion of the optical path non-parallel to thefirst portion of the optical path, and wherein the second portion of theoptical path intersects an outer surface of the fluorine-doped silicacap; and an outer cap disposed over at least a portion of thefluorine-doped silica cap, wherein the outer cap is substantially opaqueto laser energy.
 15. The apparatus of claim 14, wherein at least aportion of an inner surface of the fluorine-doped silica cap and atleast a portion of the outer-layer portion of the distal end portion ofthe optical fiber define an interface, and wherein the doped silica capincludes a doping concentration such that electromagnetic radiation fromthe optical fiber and incident on the interface is substantiallyinternally reflected within the optical fiber.
 16. The apparatus ofclaim 14, wherein the outer cap is a metallic cap, and, wherein thesecond portion of the optical path may intersect an opening of themetallic cap.